Attenuation of Side Branching in Locally Modulated Dendrite under Phase-Field Simulation

抄録

Growing from supercooled melt crystal shows complicated shapes like trees which have periodical side branching. This solidification pattern called dendrite is one of self-organized phenomena. In this phenomenon, phase and temperature distributions interact with each other during the crystal growth, since the phase transition causes latent heat. Thus, the side branches are induced from instabilities at the side wall of dendrite, though the tip of the dendrite shape was stable. In this study we have simulated pure-metal solidification by adding periodic thermal perturbations at the vicinity of the dendrite tip to investigate the shape of side branching. As a result, two types of side branches were observed when local perturbations had appropriate frequency. One type shows small wave length induced directly from perturbations, and the other large wave length expressed in comparatively away from tip. Former thin branches were attenuated to be disappeared during the latter main arms were advanced in propagation. Especially when the perturbations had small periodicity, thin side branch had not been attenuated in certain distance from modulating point. Additionally we evaluated distance from modulating point to attenuation starting point which was expected that modulation had operated side branching directly.